Wildfire is an ecological disturbance that plays an important role in ecosystem function and interacts with climate and vegetation, relationships that may be altered by ongoing climate change. Insights from paleoecology can provide context for environmental change, including the natural range of variability. Here, the Holocene fire history of a small watershed in eastern Ontario, Canada is reconstructed. A high-resolution macroscopic charcoal series was derived from the lacustrine sediment of Mud Lake, north of Gananoque, Ontario and within the Frontenac Arch. Analysis of the charcoal record estimates a mean fire-return-interval (FRI) of 175 yr/fire around Mud Lake during the Holocene, and similar mean FRIs during different time periods indicates that it has been a largely stationary fire regime. The analysis suggests that fire activity may have recently increased, but a lack of documentary fire records for the area leaves this uncertain. There is no indication that humans have significantly impacted the fire regime, though anthropogenic ignition could have played a role in the area’s recent fires. The fire regime around Mud Lake does not appear to have shifted in association with major changes in regional vegetation. Fire activity does correlate with some paleoclimate trends. The estimated fire frequency decreased around 7500 yr BP, when wetter summers became more common in eastern Canada, and a recent increase in fire frequency would parallel with more frequent incursions of dry and cool air masses into the region. During other parts of the record, however, the fire activity does not appear to reflect the major climate impacts. The fire history of Mud Lake is relevant to the ecological management of eastern Ontario’s St. Lawrence Islands National Park and its restoration of a rare, fire-dependent tree species, the pitch pine. Though predictions vary, this area’s climate may become more favorable to fire through an increase in temperature and a decrease in summer precipitation. By providing information about the natural variability of fire activity in eastern Ontario, this research can be applied towards setting appropriate management goals during future environmental change. / Thesis (Master, Environmental Studies) -- Queen's University, 2010-02-01 00:14:00.711

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Our environment (built and natural) is a thing of beauty and value, an inheritance, created by our forefathers for us and for future generations. In South Africa , conservation of cities has only recently become a reality. This study is an attempt to give a general picture of the conservation related mechanisms of townscape conservation in South Africa, with particular reference to Pietermaritzburg. Townscape conservation legislation in South Africa is presently administered in separate and unrelated sets of legislation. The National Monuments Act 28 of 1969 (chapter 2) on the one hand and the physical planning legislation (chapter 4) which is contained in a variety of provincial and local legislation on the other. There is also the Environment Conservation Act 73 of 1989 and other mechanisms (chapter 3) which incidentally promote the conservation of the South African townscape. This study will examine the legal principles available to the different mechanisms which facilitate townscape conservation, with particular reference to the City of Pietermaritzburg (chapter 5). / Thesis (LL.M.)-University of Natal, Pietermaritzburg, 1994.

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No description available.

Many stream restoration projects, as part of returning a degraded ecosystem to a healthier state, aim to restore aquatic invertebrate populations. Unfortunately, many attempts only „beautify‟ streams without achieving improvements in biodiversity. Lack of connectivity of a restoration site to a regional species pool may explain some failures. I tested this by collecting larval and adult aquatic insects from an agriculturally impacted Canterbury high country stream to evaluate connectivity of the regional species pool. The stream was surrounded by high-quality habitat in an adjacent National Park. Surrounding streams contained diverse assemblages of aquatic insects, but processes in the environment and limitations of in-stream habitat meant their adults did not always arrive at the target. In addition, oviposition habitat for hydrobiosid caddisflies was added to sections of stream and compared to un-manipulated control sections to test oviposition site limitation. The addition of oviposition habitat led to more hydrobiosid egg masses in comparison to control reaches. However, oviposition was also limited by in-stream habitat conditions, particularly the abundance of fine sediments. Sedimentation is a common pollutant in streams and is linked to decreases in habitat, food resources, and invertebrate populations. Moreover, common restoration methods, such as riparian management, have little success at reversing already high sediment levels, and are therefore insufficient to bring improvements to in-stream communities or sought-after habitat conditions. Therefore, after determining sediment was restricting sensitive invertebrate recovery at Riversdale Stream, by adding patches of high quality habitat I experimentally compared the factorial effects of sediment flushing and channel narrowing on sediment removal. Treatments improved habitat and prompted recovery of sensitive invertebrates, but an interactive effect where both flushing and channel narrowing combined created the most improved habitat conditions and the greatest improvements of invertebrate communities. Thus, while habitat improvements are an important part of restoration, features limiting species recovery such as connectivity and sedimentation, are particularly important.

Numerous streams on the West Coast drain catchments impacted by active or abandoned coal mining areas. Acid mine drainage (AMD) from coal mining can have significant negative effects on stream communities. Changing environmental ethics and regulations mean that mining companies are now encouraged to treat acid mine drainage to enable streams communities to recover. However, remediation efforts have not always been ecologically successful, and mining companies are seeking methods to enhance macroinvertebrate community recovery. Initially, I conducted an extensive survey of 45 streams draining the Stockton Plateau, which is the site of the largest opencast coal mine in New Zealand. I assessed physical and chemical conditions at each site as well as sampling benthic communities. This spatial survey showed streams impacted by acid mine drainage were comprised of chironomids and AMD-tolerant caddisflies such as Psilochorema and stoneflies such as Spaniocercoides. Un-impacted streams typically had a pH of ~5 and were dominated by mayflies (Deleatidium or Zephlebia). Analysis revealed that stream location within the landscape also had a significant influence on macroinvertebrate community composition. Another aspect of stream recovery is the ability of species to recolonise a stream. Therefore, I investigated the flight direction of adult aquatic insects in order to determine longitudinal and lateral flight preferences. No significant differences in flight direction were observed. I also investigated the influence of riparian habitat on lateral dispersal and found that a number of patterns were evident. Scrub vegetation supported higher densities of adult aquatic insects dispersing further from the stream, in contrast to the rapid decline in open bedrock and forest. Furthermore, a comparison between downstream drift and aerial flight showed significantly more individuals where drifting downstream, and this method is liable to provide rapid recolonisation of macroinvertebrates within connected stream networks. At the local scale, organic matter (comprising leaves bags and timber) and artificial moss cover were added to six streams to determine if organic matter and habitat availability would improve macroinvertebrate communities in manipulated streams. A series of floods during the experiment reduced taxonomic richness and density in manipulated streams. Overall, this study has shown that after AMD has been treated, the geographic position of streams within the landscape and lateral dispersal barriers may prevent streams being rapidly re-colonised. Therefore, to promote rapid re-colonisation of macroinvertebrates, stream remediation projects should be targeted at streams that either have un-impacted headwaters or tributaries. This will allow macroinvertebrates to drift in and re-colonise faster. In my experiment I did not find that organic matter significantly enhanced the macroinvertebrate community, but moss additions did provide additional habitat for macroinvertebrates. These results highlight the importance that disturbance events can have on remediation projects.

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This study examines the sustainability of historic windows in comparison to modern replacement windows. A sustainable product is defined as one that lasts multiple generations without causing harm to the environment, either in its production, maintenance, or disposal. Historic windows are perceived as energy inefficient and are often removed and replaced. Historic windows can, however, be augmented to perform similarly to replacement windows. To determine sustainability, window materials were evaluated based on their life span, life cycle, energy efficiency, maintenance, and disposal. In general, historic windows are long lasting and retaining them conserves materials and energy used in their production. Based on the above criteria, historic wood windows were found to be highly sustainable due to their excellent energy performance (with the addition of storm windows), durability (with regular maintenance), and low environmental impact in processing and disposal. / Defining sustainability -- History of windows -- Window materials -- Windows and energy -- Embodied energy and life cycle analysis -- Durability -- Findings. / Department of Architecture